Converting Sunlight to
by Clare Coppa
In Vision 21 [Nov. 8], Time magazine projects, Rooftop solar panels will supply electricity
to our appliances and to a basement fuel cell, which will produce
hydrogen. When the sun is not shining, the cell will operate in
reverse, using the hydrogen to make electricity.
Shortening the path to home-produced electricity, George Kelly,
a member of ASTM Committee E-44 on Solar, Geothermal and Other
Alternative Energy Sources, has worked in the solar industry nearly
two decades. His latest project is an array of photovoltaic (PV) modules
that converts sunlight to electricity which he installed in 1998
on the roof of his home in Mt. Airy, Md. A home weather station
and a data acquisition system compare the amount of sunlight available
to the amount of power produced. Its kind of a hobby in that
I like doing all the wiring and fiddling around with the gadgets,
Does Kellys system power his all-electric 1600 sq. ft. (150 sq.
meter) home and completely run appliances for Kellys family of
four? No, but its a step toward future all-solar homes. The
cost of fossil fuels will continue to rise, the cost of solar
is going to continue to fall, and as people use more solar, the
price will drop even further and then it will really take off,
he predicts. In the last maybe four to five years, there has
been a big emphasis on grid-connected applications for residential
or commercial rooftops.
Kelly helped to develop the easy-to-install interlocking PV modules
on his roof with BP Solarex, a manufacturer of solar products
in Frederick, Md., and his employer of 19 years. Eight PV modules
with no moving parts and nothing to wear out feed direct current
(DC) into a small electric box on the side of the house which
connects a cable to a basement inverter that converts the DC to
about 60 kilowatt hours of AC (alternating current) monthly.
The point of the residential roof market, says Kelly, is just
the available area. There are millions of houses in the U.S. with
hundreds and thousands of square miles of roof area. If you covered
all of it with solar modules, instead of just sitting there, it
could be producing power to be fed into the electric grid. Instead
of needing new power plants, either coal, hydroelectric, or whatever,
you could use all of the empty roof top space to generate electricity.
Progressing swiftly, Kelly added a ninth module which he also
helped to develop that eliminates the need for an inverter in
the basement. An inverter on the back of the module converts sunlight
into AC electricity on the roof and feeds the house current.
Anything that runs off of electricity can be run with PV modules,
he explains. Especially in places where its sunny most of the
year, like Phoenix, or southern California. In some remote areas
where it would be very expensive to bring in a power line, it
is more cost effective to install solar modules. There are already
completely solar-powered homes that are independent of the local
Solar research boomed after the 1970s oil crisis with funding
from the Carter administration. Kelly entered the field in 1980
after attaining a B.S. in architecture from Catholic University,
Washington, D.C. Shortly after graduation, he joined BP Solarex
and helped to produce PV solar modules that fueled NASA missions.
Probably the most famous one that we worked on was the Magellan,
which went to Venus, orbited it, and made maps, he recalls.
With members of ASTM Subcommittee E44.09 on Photovoltaic Electric
Power Conversion, Kelly wrote Standard E 2047, Test Method for
Wet Insulation Integrity Testing of Photovoltaic Arrays.
Its been the hope all along for the PV industry that oil prices
were going to get really high and fossil fuels were going to run
out so that people would have to use solar, wind, or other alternate
energy. It hasnt really happened that way. If you asked somebody
in 1979 when the oil would run out they would have said 10 or
15 years. Well here we are 20 years later and there is still a
lot of oil around and the prices havent shot through the roof
and it hasnt disappeared the way people thought. But, sooner
or later it will. //